JP3754606B2 - Reluctance type resolver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reluctance resolver as a sensor for detecting the motion speed and motion position of a movable part of a rotary or direct acting motor, and in particular, detection caused by leakage magnetic flux from a motor rotor, an electromagnetic brake or the like. It relates to error reduction.
[0002]
[Prior art]
FIG. 3 is a cross-sectional view of an example of a conventional reluctance resolver cut in the radial direction. FIG. 4 is a block diagram showing an example of a detection device for detecting a rotational position from the reluctance resolver of FIG. In FIG. 3, the stator 1 has eight exciting teeth 2, 3, 4, 5, 6, 7, 8, and 9 made of a magnetic material, arranged at equal intervals on the inner periphery thereof. Are wound with excitation windings 12, 13, 14, 15, 16, 17, 18, 19 respectively. This excitation winding generates magnetic fluxes in opposite directions to the excitation teeth 2, 4, 6, 8 and excitation teeth 3, 5, 7, 9 when the excitation signal is input, and the sum of the magnetic fluxes passing through the excitation teeth. Is wound to be zero. The rotor (movable element) 11 is made of a magnetic material, and has 18 convex portions at regular intervals on the outer periphery thereof, and each convex portion is disposed so as to face the excitation teeth of the stator 1. The rotor 11 is fixed to the input shaft 10 so as to rotate in conjunction with the rotational movement of the input shaft 10. In such a reluctance type resolver, when the rotor 11 rotates, the permeance of each excitation winding causes the period of the protrusion pitch of the rotor 11 due to the gap fluctuation between the protrusion on the rotor 11 side and the excitation tooth of the stator 1. It changes with. In addition, the phase of the change in permeance with the adjacent excitation winding is a phase different from ¼ pitch of the convex portion pitch.
[0003]
In the detection device of FIG. 4, the excitation windings 12, 16, 14, 18, 13, 17, 15, 19 of the reluctance resolver of FIG. 3 are excited by the excitation signal current SIN (ωt) from the excitation signal generator 20. ing. The excitation signal generator 20 shapes the rectangular wave signal EXP from the timing generator 30 to generate and output a sinusoidal excitation signal current SIN (ωt). Excitation windings 12 and 16, 13 and 17, 14, 14 and 18, 15 and 19 that are wound around opposing excitation teeth and change in permeance (magnetic resistance) in the same phase are connected in series, and current detection resistors 21, 22, and 23 are connected in series. , 24 are connected in series. As a result, the currents flowing through each set of excitation windings can be detected as voltage signals VCP, VCN, VSP, and VSN, respectively. The excitation windings wound around the opposing excitation teeth and having the same phase permeance change are connected in series because the two excitation windings are averaged even when the center of the stator and the rotor is deviated. This is because the effect on the accuracy of position detection is reduced.
[0004]
Since the currents flowing through the excitation windings 12 and 16, 13 and 17, 14 and 18, 15 and 19 of each set change in proportion to changes in winding permeance, the rotation angle of the rotor 11 is θ, the coefficient is α, Assuming β, the signals VCP, VCN, VSP, and VSN can be expressed by the following approximate expression.
[0005]
[Expression 1]
VCP = (α + βCOS (14θ)) SIN (ωt) (1)
VCN = (α−βCOS (14θ)) SIN (ωt) (2)
VSP = (α + βSIN (14θ)) SIN (ωt) (3)
VSN = (α−βSIN (14θ)) SIN (ωt) (4)
[0006]
Signals VCP and VCN, and VSP and VSN are subtracted by differential amplifiers 25 and 26, respectively, and are arithmetically amplified to signals VC and VS, respectively. The signals VC and VS are expressed by equations (5) and (6).
[0007]
[Expression 2]
VC = 2βCOS (14θ) SIN (ωt) (5)
VS = 2βSIN (14θ) SIN (ωt) (6)
[0008]
The signals VC and VS are converted into digital signals DC and DS by the AD converters 27 and 28 at the timing when SIN (ωt) = 1 by the conversion command signal CNV synchronized with the excitation signal from the timing generator 30. Therefore, the signals DC and DS are expressed by equations (7) and (8).
[0009]
[Equation 3]
DC = 2βCOS (14θ) (7)
DS = 2βSIN (14θ) (8)
[0010]
The digital signals DC and DS are subjected to two-variable arc tangent calculation by digital processing by an interpolation calculator 29, and a signal PO is output. Here, the arc tangent calculation result of the digital signals DC and DS is 14θ, and the signal PO is the rotational position of the input shaft 10.
[0011]
As described above, the reluctance resolver of FIG. 3 has a simple winding structure in which one excitation winding is wound around one tooth on the stator side, and detects the position θ of the input shaft with 14 times the sensitivity. Can do. Such a resolver that can detect the position of the mover with 14 times the sensitivity is generally referred to as a resolver having a shaft angle multiplier of 14X.
[0012]
[Problems to be solved by the invention]
However, when detecting the motor speed and position of the motor rotor using the conventional reluctance resolver shown in FIGS. 3 and 4, the motor rotor permanent magnet or the braking electromagnetic brake as shown by the dotted line in FIG. Accurate measurement is hindered by the influence of the leakage flux NF. That is, since the leakage flux NF changes due to the gap fluctuation between the rotor-side convex portion and the stator-side excitation tooth, it changes in proportion to the permeance change of each excitation winding. For this reason, when the rotor 11 rotates, the leakage magnetic flux passing through each excitation winding changes, and a noise current is generated in the excitation winding in proportion to the differential amount.
[0013]
Specifically, assuming that the angular velocity when the rotor is movable is v and the coefficient is γ, the signals VCP, VCN, VSP, and VSN in consideration of the noise current can be expressed by the following approximate expressions.
[0014]
[Expression 4]
VCP = (α + βCOS (14θ)) SIN (ωt) −14γvSIN (14θ) (7)
VCN = (α−βCOS (14θ)) SIN (ωt) + 14γvSIN (14θ) (8)
VSP = (α + βSIN (14θ)) SIN (ωt) −14γvCOS (14θ) (9)
VSN = (α−βSIN (14θ)) SIN (ωt) + 14γvCOS (14θ) (10)
[0015]
Further, the signals VC and VS which are the difference between the signals VCP and VCN and VSP and VSN are expressed by equations (11) and (12).
[0016]
[Equation 5]
VC = 2βCOS (14θ) SIN (ωt) −28γvSIN (14θ) (11)
VS = 2βSIN (14θ) SIN (ωt) −28γvCOS (14θ) (12)
[0017]
From the equations (11) and (12), the digital signals DC and DS can be expressed by the following equations.
[0018]
[Expression 6]
DC = 2βCOS (14θ) −28γvSIN (14θ) (13)
DS = 2βSIN (14θ) −28γvCOS (14θ) (14)
[0019]
Equations (13) and (14) can be transformed into the following equations by the addition theorem of trigonometric functions when δ = SQRT (4β · β + 728γ · γ · v · v).
[0020]
[Expression 7]
DC = δCOS (14θ + ATAN (14γv / β)) (15)
DS = δSIN (14θ−ATAN (14γv / β)) (16)
[0021]
When digital signals DC and DS shown in Expressions (15) and (16) are subjected to arc tangent calculation of two variables by the interpolation calculator 28, the signal PO becomes the following expression.
[0022]
[Equation 8]
PO≈14θ-ATAN (14γv / β) COS (28θ) (17)
[0023]
Here, 14γv is sufficiently smaller than β, so
[0024]
[Equation 9]
PO≈14 (θ + γv / βCOS (28θ)) (18)
[0025]
Further, when the equation (18) is converted into a general equation of a resolver with a shaft angle multiplier NX:
[Expression 10]
PO = N (θ + γv / βCOS (2Nθ)) (19)
[0027]
It can be expressed as
[0028]
From the above, the influence of the position detection error due to the magnetic flux leakage from the motor increases in proportion to the angular velocity v and the shaft angle multiplier N, and a position detection error that pulsates 2N times per revolution is generated. This position detection error is small when the resolver shaft multiple angle is small, the excitation signal frequency ω is sufficiently high, and the moving speed is low, as shown in equations (11) and (12), the noise component due to leakage magnetic flux is in the low range. It can be removed with a low-pass filter or the like. However, in recent years, in order to increase the resolution of position detection, there is a tendency to increase the resolver shaft multiple angle, and the moving speed of the electric motor has been increased. Therefore, there is a limit to the removal by the low-frequency cut filter. Even if the position detection error is only at a level that does not pose a problem, in recent motor speed control, the position detection value is detected by differential calculation. The effect of leakage magnetic flux becomes more serious as it moves faster.
[0029]
The present invention has been made in view of the above circumstances, and has a highly accurate winding structure that is less susceptible to leakage flux from a permanent magnet of an electric motor rotor or an electromagnetic brake for braking while having a winding structure that is easy to manufacture. An object of the present invention is to provide a reluctance type resolver capable of speed detection and position detection.
[0030]
[Means for Solving the Problems]
The present invention for solving the problems of the conventional example has a plurality of exciting teeth wound with exciting windings, and includes a stator made of a magnetic material and a magnetic convex portion, and the magnetic convex portion is A reluctance type that detects the position of the mover by detecting the current or voltage of the mover arranged at a different phase according to the movement of the mover arranged to face the excitation tooth and the mover In the resolver, the excitation winding is wound around each excitation tooth such that the direction of the magnetic flux passing through each excitation tooth is the same direction, and the stator is a bypass magnetic path through which the magnetic flux in the direction opposite to the magnetic flux of the excitation tooth passes. It is characterized by having teeth. Thereby, since there are bypass magnetic path teeth, the excitation winding can be wound in a direction that is not easily affected by the leakage magnetic flux, and the speed detection accuracy can be improved.
[0031]
Further, the present invention for solving the problems of the conventional example includes a set of exciting teeth adjacent to each other and arranged so that the change in magnetic resistance due to the movement of the mover has the same phase. By directly canceling the excitation winding wound around each of the excitation teeth, the influence of leakage magnetic flux can be reduced, and the speed and position detection accuracy can be improved. That is, the present invention has a plurality of excitation teeth around which excitation windings are wound, and includes a stator made of a magnetic material and a magnetic convex portion, and the magnetic convex portion is arranged to face the excitation teeth. In a reluctance resolver that detects a position of the mover by detecting a current or a voltage of the excitation winding that changes in a different phase according to the movement of the mover and the mover, the excitation winding includes: For each set of adjacent excitation teeth, each excitation tooth is wound and connected in series so that the directions of magnetic flux passing through each excitation tooth are opposite to each other, and the pitch of each excitation tooth is movable for each set. Excitation teeth are arranged on the stator so as to be equal to an integral multiple of the pitch of the magnetic projections of the child.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a reluctance resolver according to an embodiment of the present invention cut in a radial direction. Here, components having the same configuration as in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted. The stator 31 has 16 teeth made of a magnetic material arranged at equal intervals on the inner periphery thereof, of which 8 teeth (corresponding to excitation teeth) 42, 43, 44, 45, 46, 47, 48, 49 are wound with exciting windings 32, 33, 34, 35, 36, 37, 38 and 39, respectively. Further, no winding is wound around the remaining 8 teeth (corresponding to bypass magnetic path teeth). Further, in the stator 1, four sets of excitation windings 32 and 36, 33 and 37, 34 and 38, 35 and 39 are connected in series, and when an excitation signal is input to the excitation winding, teeth 42, In 43, 44, 45, 46, 47, 48, and 49, excitation windings are wound around the rotor 11 so that magnetic flux in the same direction is generated. Thus, when an excitation signal is input to the excitation winding, the eight bypass magnetic path teeth that are arranged between the excitation teeth and are not wound with the windings are excited teeth 42, 43, 44, 45, 46. , 47, 48, 49 and a magnetic flux in the direction opposite to the direction of the rotor 11 is generated to serve as a bypass magnetic path.
[0033]
The case where the reluctance resolver of FIG. 1 is detected in the same manner as in FIG. 3 using the position detection device of FIG. 4 will be described. Four types of excitation windings 32 and 36, 33 and 37, 34 and 38, 35 and 39 are used. The windings correspond to the four types of windings of the conventional reluctance resolver excitation windings 12, 16, 13, 17, 14, 18, 15, and 19, and change in permeance with respect to the movement of the rotor 11 as a mover. Is almost equivalent to the conventional one. That is, the position of the reluctance resolver shown in FIG. 1 can be detected in the same manner as the resolver shown in FIG. 3 even when the position detection device shown in FIG. 4 is used. On the other hand, when the leakage magnetic flux NF as shown by the dotted line in FIG. 5 is generated, the direction of the noise current generated by the leakage magnetic flux in the excitation windings 33, 37, 35, 39 and the excitation windings 13, 17, 15, 19 Therefore, when the reluctance resolver of FIG. 1 is used and the position detection device of FIG. 4 detects the position and the like, the signals VSP and VSN have the following approximate expressions.
[0034]
## EQU11 ##
VSP = (α + βSIN (14θ)) SIN (ωt) + 14γvCOS (14θ) (20)
VSN = (α−βSIN (14θ)) SIN (ωt) −14γvCOS (14θ) (21)
[0035]
Therefore, the signal VS which is the difference between VSP and VSN is expressed by Equation (22).
[0036]
[Expression 12]
VS = 2βSIN (14θ) SIN (ωt) + 28γvCOS (14θ) (22)
[0037]
From equation (22), the digital signal DS when SIN (ωt) = 1 is given by equation (23).
[0038]
[Formula 13]
DS = 2βSIN (14θ) + 28γvCOS (14θ) (23)
[0039]
Here, the equation (23) can be transformed into the following equation by the addition theorem of trigonometric functions.
[0040]
[Expression 14]
DS = δSIN (14θ + ATAN (14γv / β)) (24)
[0041]
Further, since the signal DC is the same as the equation (15), when the digital signal DC, DS is subjected to two-variable arc tangent calculation by the interpolation calculator 28, the signal PO becomes the equation (25).
[0042]
[Expression 15]
PO = 14θ + ATAN (14γv / β) (25)
[0043]
Here, if it is considered that 14γv is sufficiently smaller than β, Expression (26) is obtained.
[0044]
[Expression 16]
PO = 14 (θ + γv / β) (26)
[0045]
As shown in the equation (26), the influence of the leakage magnetic flux when the position is detected by the reluctance type resolver of FIG. 1 occurs as an offset error of the position proportional to the rotation speed, and no pulsation component is generated. Therefore, the speed detection value obtained by differentiating the position detection value is not affected by the speed error due to the leakage magnetic flux. Note that the offset error of the position proportional to the speed is sufficiently small compared with the tracking delay due to the position control or the like, so that even if 14γv is much larger than β, ATRAN (14γv / β)) exceeds ± π / 2. And sufficient accuracy can be achieved.
[0046]
Next, another embodiment of the present invention will be described based on the drawings. FIG. 2 is a cross-sectional view of a reluctance resolver according to another embodiment of the present invention cut in the radial direction. 2, those having the same configuration as the conventional one shown in FIG. 3 are denoted by the same reference numerals and detailed description thereof is omitted. The stator 51 of the present embodiment has eight excitation teeth 62, 82, 63 and 83, 64 and 84, 65 and 85, 66 and 86, each having two excitation teeth adjacent to each other on the inner periphery. , 67 and 87, 68 and 88, 69 and 89 are arranged. The pairs of excitation teeth are arranged at equal intervals, and the interval (pitch) between the two excitation teeth in the set is arranged to be the same pitch that is an integral multiple of the pitch of the convex portions of the stator 11. . As a result, the permeance between the pair of excitation teeth and the stator 11 changes in the same phase. Eight sets of teeth 62 and 82, 63 and 83, 64 and 84, 65 and 85, 66 and 86, 67 and 87, 68 and 88, 69 and 89 have excitation windings 52 and 72, 53 and 73, 54, respectively. And 74, 55 and 75, 56 and 76, 57 and 77, 58 and 78, 59 and 79 are wound. The two excitation windings in each set are connected in series, and when an excitation signal is input to the excitation winding, magnetic fluxes in opposite directions are generated from the two excitation teeth in the set toward the rotor side. It has come to occur. From the above, in the resolver of FIG. 2, the two excitation teeth in each group have the same phase of change in magnetic resistance with respect to the movement of the rotor 11 as the mover, and the magnetic flux passes through the two excitation teeth in the pair. The sum of is zero. In such a reluctance resolver, the excitation windings 52, 72, 56, 76, 53, 73, 57, 77, 54, 74, 58, 78, 55, 75, 58, 78, 56, 76, 59, 79 The four types of excitation windings correspond to the four types of excitation windings of the conventional excitation windings 12 and 16, 13 and 17, 14 and 18, 15 and 19, and the permeance change with respect to the movement of the rotor 11 Therefore, position detection can be performed using the conventional position detection apparatus shown in FIG.
[0047]
Considering the influence of the leakage magnetic flux in the resolver of FIG. 2, the two excitation teeth in each group have the same phase permeance change with respect to the movement of the rotor 11. The same leakage flux passes. Therefore, the noise current generated in the two excitation windings in each group is at the same level, and the excitation windings are connected in series with opposite phases. For this reason, the noise currents cancel each other, and the noise current due to the leakage magnetic flux flowing in each pair of exciting windings is removed.
[0048]
The reluctance resolver that outputs the four signals VCP, VCN, VCP, and VSN out of phase has been described so far. However, such a resolver performs position detection if a signal having a phase difference of 2 or more is obtained. Therefore, the present invention is not limited to a four-phase output type reluctance resolver, and may be a reluctance type resolver that outputs signals with two or three phases shifted. In the above description, the rotary reluctance resolver has been described. However, a linear reluctance resolver in which a stator and a rotor (movable element) are linearly developed may be used.
[0049]
【The invention's effect】
According to the reluctance type resolver of the present invention, one winding is wound around one exciting tooth, and it has a structure that is easy to manufacture, but against leakage magnetic flux from a permanent magnet of an electric motor rotor or an electromagnetic brake for braking. Therefore, it is possible to perform highly accurate speed detection and position detection that are difficult to be affected.
[Brief description of the drawings]
FIG. 1 is a radial sectional view of a reluctance resolver according to an embodiment of the present invention.
FIG. 2 is a radial sectional view of a reluctance resolver according to another embodiment of the present invention.
FIG. 3 is a cross-sectional view of a conventional reluctance resolver cut in a radial direction.
FIG. 4 is a configuration block diagram of a reluctance resolver detection device.
FIG. 5 is an explanatory diagram showing an example of leakage magnetic flux coming from the axial direction with respect to the reluctance resolver.
[Explanation of symbols]
1,31,51 Stator, 10 Input shaft, 11 Rotor, 20 Excitation signal generator, 25, 26 Differential amplifier, 27, 28 AD converter, 29 Interpolator, 30 Timing generator

Claims (2)

A plurality of exciting teeth wound with exciting windings, and a stator made of a magnetic material;
A mover provided with a magnetic convex part, the magnetic convex part being arranged so as to face the excitation tooth;
In a reluctance resolver that detects the position of the mover by detecting the current or voltage of the excitation winding that changes in different phases according to the movement of the mover,
The exciting winding is wound around each exciting tooth so that the direction of the magnetic flux passing through each exciting tooth is the same direction, and the stator has a bypass magnetic path tooth that passes a magnetic flux in a direction opposite to the magnetic flux of the exciting tooth. A reluctance type resolver characterized by that. A plurality of exciting teeth wound with exciting windings, and a stator made of a magnetic material;
A mover provided with a magnetic convex part, the magnetic convex part being arranged so as to face the excitation tooth;
In a reluctance resolver that detects the position of the mover by detecting the current or voltage of the excitation winding that changes in different phases according to the movement of the mover,
The excitation winding is wound around each excitation tooth and connected in series so that the direction of the magnetic flux passing through each excitation tooth is opposite to each other for each set of excitation teeth adjacent to each other,
A reluctance resolver, wherein excitation teeth are arranged on the stator so that the pitch of each excitation tooth is equal to an integral multiple of the pitch of the magnetic projections of the mover for each set.

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